IF THERE is a social or economic need, Democratic presidential front-runner Hillary Clinton has a tax credit to match. She’s proposed one for businesses that institute profit-sharing plans (cost: $20 billion over 10 years); another for hiring disabled veterans; and, as of last week, a tax credit worth up to $1,200 to help families defray the cost of caring for their elderly members at home (a $10 billion, 10-year item). Coming soon: changes to Social Security to benefit workers who take time off to care for the elderly.

When it comes to paying for these “targeted” benefits, plus her other promises such as universal preschool, however, the former secretary of state has a clear principle: none of the 97 percent of U.S. households that earn $250,000 or less per year will be asked to contribute higher taxes.

If this strikes you as implausible — the Democratic equivalent of the no-tax-hike pledge Republican candidates regularly impose on themselves — we agree. There is simply no way that the federal government can meet its current fiscal commitments, plus the increased demands of an aging population, and provide the new forms of middle-class relief and business tax relief Ms. Clinton promises, while tapping only the top 3 percent of earners.

To the contrary, if the U.S. government is to do all those things and still reduce its long-term debt to a more manageable share of the total economy, middle- and upper-middle-class Americans are going to have to contribute more, not less. Examples: You can’t have securely funded national infrastructure programs without increasing the gas tax for the first time since 1993; and one way to shore up Social Security’s trust fund would be to raise the maximum amount of taxable earnings from the current level of $118,500.

All of this would be true, by the way, even if Ms. Clinton were proposing direct spending to accomplish her policy goals, as opposed to cluttering up the tax code with more special breaks and making it harder to reform. Ms. Clinton contrasts her approach with that of her chief opponent, Sen. Bernie Sanders (I-Vt.), who would enact vast new spending programs, from free state-college tuition to increased Social Security benefits, and pay for them, in part, with tax increases on the middle class. She argues correctly that many new benefits Mr. Sanders wants would be available regardless of income, so that taxpayers of lesser means could end up subsidizing the rich.

But the truth is there isn’t really all that much difference between Ms. Clinton’s promise to soak the top 3 percent and Mr. Sanders’s promise to get the money he needs from the “billionaire class.” Both are selling the voters an unrealistic guarantee; both are ignoring the need for deficit reduction along with a modernized social safety net. Like the GOP candidates, the Democrats are offering ideas poll-tested and calculated to appeal to the party base, rather than creative approaches to the country’s fiscal predicament. Eventually, our leaders will have to stop pandering to the middle class, hopefully before a crisis forces them to face facts.